Device for ultrahigh frequencies



y 6, 1952 D. ZAAYER 2,596,002

DEVICE FORULTRAHIGHFREQUENCIES Filed July 12, 1946 INVENTOR. DAVID ZAAYER A7 TOPNFY Patented May 6, 1952 DEVICE FOR ULTRAHIGH FREQUENCIESDavid Zaayer, Eindhoven, Netherlands, assignor to Hartford National Bankand Trust Company, Hartford, Conn., as trustee Application July 12,1946, Serial No. 682,986 In the Netherlands February 22, 1943 Section 1,Public Law 690, August 8, 1946 Patent expires February 22, 1963 Claims.1

This invention relates to a device for ultra-high frequencies comprisingat least one discharge tube, whose wall consists of insulating materialand which has at least one anode and one cathode, at least the anodecircuit including a resonator which is tuned to the operating frequencyand consists of two coaxial conductors and is at least substantiallyclosed on all sides.

In the construction of such a device one is confronted with variousproblems. To obtain a satisfactory efficiency it is necessary, forinstance, that theconnecting leadsbetween the resonator and theelectrodes of the discharge tube(s) should be very short, since theseleads cause considerableradiation and conduction losses which areproportional to the length of the connecting leads.

A second problem one is faced with is related with the heating of theseals of the said connecting leadsi. e. those points of the wall of thetube, which may consist of glass, where the conductors conveying thehigh-frequency current are passed through this wall. This heating is dueto the losses in the leads and may render the tube defective.

The present invention envisages a construction of the device referred toin the preamble, by which the aforesaid problems are solvedsatisfactorily. According to the invention this is achieved by means ofa construction in which the inner conductor of the resonator is tubular,and one'en'd'of the inner conductor, which is not connected to the outerconductor, surrounds the discharge tube coaxially over a large part ofthe length of the anode in such a manner that the anode iscapacitatively coupled to the inner conductor.

When making use of the construction accordingto the invention theconnecting lead between anode and resonator, which lead causes thelarger part of the losses because the voltages are a maximum at theanode, may be entirely dispensed with. Furthermore, since the tube islodged at least for the greater part within the closed resonator, theradiation losses due to electromagnetic radiation from the electrodethemselves are only smal1 and the remaining connecting leads conveyinghigh-frequency current can also be kept short; in a suitable form ofconstruction set out hereinafter the part of the grid lead outside thetubemay even be dispensed with completely.

In the construction according to the invention the seals are not heatedor only to a slight degree,

since in this case the connecting leads for the electrodes, at least forthe anode, passing through the insulating wall of the tube only servefor the supply of the feed voltages required for the electrodes, so thatpractically no losses occur in these leads.

In order that the invention may be clearly understood and readilycarried into effect, it will now be described more fully with referenceto the accompanying drawing which represents a preferred embodiment of adevice according thereto in axial section.

The form of construction of a device according to the inventionrepresented in the single figure of the drawing serves for theproduction of oscillations having the natural frequency of a resonator Iwhich consists of a tubular inner conductor 3 and an outer conductor 5surrounding the latter coaxially. The inner conductor 3 is connected atone end to the corresponding end of the outer conductor 5, through theintermediary of a conductive disc 1. The other end of the outerconductor is terminated by a conductive disc 9 so that the resonator isclosed practically on all sides. The resonator l is included in theanode circuit of a discharge tube ll having an envelope I2 of insulatingmaterial. According to the invention the tube l l is lodged within thetubular inner conductor 3 and this tube is coaxially surrounded by theend of the inner con ductor 3, which is not connected to the outerconductor, over a great part of the length of the anode 13 in such amanner that the anode I3 is capacitatively connected to the innerconductor 3.

At the end of the inner conductor connected to the disc 1 a potentialnode occurs, whereas a potential loop appears at the end to which theanode is coupled.

For supplying the required feed voltage to the anode conveying ahigh-frequency voltage use is made of coaxial auxiliary conductor [5having the same shape and substantially the same section as the innerconductor 3 and being incorporated in the tubular inner conductor 3 insuch a manner as to be insulated therefrom. One end of this auxiliaryconductor is connected through a short connecting lead to the anode 13,whereas the other end, which preferably slightly projects from theresonator I, is connected, through a connecting lead I! outsideresonator, to a source of anode voltage I9. As a result of the shortdistance in this construction between the cylindrical surface of theauxiliary conductor 15 and the inner surface of the inner conductor 3these conductors are tightly coupled capacitatively and constitute anassembly in electrical respect in regard to the operating frequency, sothat the end of the conductor I projecting from the resonator and thelead I'I connected to this end does not have a high-frequency voltagerelatively to earth.

The grid 2| of tube II is connected to the centre of the disc 9 throughthe intermediary of one or more connecting leads which are connected inparallel and are as short as possible. This centre and the end of theinner conductor 3 surrounding the anode constitute the electricterminals of the resonator. Consequently, the grid and the anode of thetube H are connected respectively to the electric terminals of theresonator.

The device represented in the drawing is of a type known per se, inwhich the resonant circuit is interposed between grid and anode and thecathode is connected to a point of a capacitative potentiometerconnected in parallel with the resonant circuit and consisting of thecathodeanode capacity and the cathode-grid capacity. Between the cathodeand the earthed outer wall of the resonator is included a circuit thatis substantially tuned to the frequency of the oscillations to begenerated and in the device shown in the drawing is constituted by acoaxial transmission line consisting of the conductors 23 and 25.. Theouter conductor 23 is connected to the earthed wall 9 of the resonator Iin the proximity of the end facing the cathode, whereas the innerconductor 25 is earthed at the end of the resistance 3| remote from thecathode, which resistance serves for the obtainment of the required gridbias. The inner conductor 25, which serves at the same time for thesupply of the required heating current, is tubular and contains theother heating lead which is insulated therefrom. The disc 9 is providedwith a central aperture through which the two heating leads areconnected to the cathode 21. The feed voltage for the cathode issupplied by a supply 29 one of whose terminals is earthed across thecathode resistance 3|. The resistance 3I is preferably not bridged by ashort-circuit condenser so that a negative back-coupling is present forthe low frequencies thus preventing the tube II from oscillating at thedesired frequency and. at the same time at a low frequency.

The transmission line 23, 25 is tunable by means of a short-circuitbridge 33 which is movable in an axial direction. In view of the factthat the outer conductor 23 is earthed in regard to direct current,whereas the inner conductor 25 has a positive direct voltage withrespect to earth, the bridge 33 is realised in such a manner that thereis no electrical connection in regard to direct current between theconductors 23 and 25.

The device set out above generates oscillations whose frequency isdetermined by the natural frequency of the resonator I. The frequency ofthe generated oscillations is variable by means of a conductive piston4| which is movable in an axial direction with the aid of a clasp 43projecting from the resonator.

The generated oscillations may be taken from the resonator by means of aloop 45 coupled to the magnetic field within the resonator.

In order that the coupling between the inner conductor 3 and the anodeI3 may be'controlled the inner conductor 3 is so realised as to bemovable in an axial direction relatively to the tube II secured to thedisc 9. With the aid of a screw 41 the inner conductor 3 can be fixed inthe desired position.

The envelope I2 of tube II extending for the greater part of thehigh-frequency electric field between the anode I3 and .the end'of theinner conductor 3, use is preferably made of a tube II with an envelopeof a material having low dielectric losses such as quartz.

For carrying off the heat dissipated by the anode I3 use is made ofliquid cooling in the device shown in the drawing. To this end the innerconductor 3 has a double wall and is equipped with two partitionsextending in a plane through the axis of the inner conductor anddividing the space between the two walls of the inner conductor 3 intotwo compartments which communicate with each other at the end of theinner conductor surrounding the anode. These partitions are normal tothe plane of the drawing; for clarity, however, they have not beenrepresented. The cooling liquid can be supplied through an inlet opening49 at the end of the inner conductor remote from the anode I3 to one ofthe two compartments, and upon traversing the other compartment of theinner conductor it is carried off through an outlet opening 5|. Topromote as much as possible the transfer of heat between the anode I3and the inner conductor 3 preferably the inner side of the innerconductor 3 is coated with a black layer at the anode I3. When the tubeI I is of the usual type, where the anode consists of carbon, aneffective transfer of the heat to be dissipated is obtained in thismanner by radiation.

In the device according to the invention cooling by air instead ofliquid cooling may be used, if desired; in this case the cooling air maybe blown through an aperture, for instance through the aperture throughwhich pass the heating current conductors the air then passing betweenthe wall of the tube II and the inner wall of the inner conductor 3 andescaping to the outside through the inner conductor What I claim is:

1. An ultra high frequency electronic device comprising an electrondis-charge tube having an insulating envelope with a cathode, a grid andan elongated tubular anode enclosed therein, said grid and said cathodebeing coaxially positioned within said anode, and a reentrant cavityresonator having a tubular outer conductor surrounding said tube and atubular inner conductor coaxial with said outer conductor and connectedto one end thereof, the other end of said outer conduotor being closed,said tube being received within said inner conductor to an' extent atwhich a portion of said anode is surrounded by said inner conductor toeffect capacitive coupling" for high frequencies therebetween, said'envelope acting as a dielectric between said anode and said'innerconductor, said grid being connected to said closed end of said outerconductor.

2. An ultra high frequency electronic device comprising an electrondischarge tube having an insulating envelope with a cathode, a grid andan elongated tubular anode enclosed therein, said grid and said cathodebeing concentrically ar ranged within said anode, a reentrant cavityresonator having a tubular outer conductor surrounding said tube and atubular inner conductor coaxial with said outer conductor and connectedto one end thereof, the other end of said outer conductor being closed,said tube being received within said inner conductor to an extent atwhich a portion of said anode is surrounded by said inner conductor toeffect capacitive coupling for high frequencies therebetween, saidenvelope acting as a dielectric between said anode and said innerconductor, said grid being connected to said closed end of said outerconductor, a cylindrical conductor coaxially disposed within said innerconductor, and means to apply an energizing potential through saidcylindrical conductor to the anode of said tube.

3. An ultra high frequency electronic device comprising an electrondischarge tube having an insulating envelope with a cathode, a grid andan elongated tubular anode enclosed therein, said grid and said cathodebeing coaxially positioned within said anode, a reentrant cavityresonator having a tubular outer conductor surrounding said tube and atubular inner conductor coaxial with said outer conductor and connectedto one end thereof, the other end of said outer conductor being closed,said tube being received within said inner conductor to an extent atwhich a portion of said anode is surrounded by said inner conductor toeffect capacitive coupling for high frequencies therebetween, saidenvelope acting as a dielectric between said anode and said innerconductor, said grid being connected to said closed end of said outerconductor, a cylindrical conductor coaxially disposed within said innerconductor, means to apply an energizing potential through saidcylindrical conductor to the anode of said tube, and an annular shortingbridge slidably arranged between said inner and outer conductors.

4. An ultra high frequency electronic device comprising an electrondischarge tube having an insulating envelope with a cathode, a grid and.an elongated tubular anode enclosed therein, said grid and said cathodebeing coaxially positioned within said anode, a reentrant cavityresonator having a tubular outer conductor surrounding said tube and atubular inner conductor coaxial with said outer conductor and connectedto one end thereof, the other end of said outer conductor being closed,said tube being received within said inner conductor to an extent atwhich a portion of said anode is surrounded by said inner conductor toeffect capacitive coupling for high frequencies therebetween, saidenvelope acting as a dielectric between said anode and said innerconductor, said grid being connected to said closed end of said outerconductor, a cylindrical conductor coaxially disposed within said innerconductor, means to apply an energizing potential through saidcylindrical conductor to the anode of said tube, an annular shortingbridge slidably arranged between said inner and outer conductors, acoaxial transmission line having one end of its outer lead secured tosaid closed end of said outer conductor and having the corresponding endof its inner lead connected to the cathode of said tube, a capacitivebridge interposed between said inner and outer leads for tuning saidline, and a cathode resistor connected between the other end of saidinner lead and the outer surface of said outer conductor.

5. An ultra high frequency electronic device comprising an electrondischarge tube having a tubular insulating envelope with a cathode, agrid and an elongated tubular anode enclosed therein, said grid and saidcathode being coaxially disposed within said anode, and a reentrantcavity resonator having a tubular outer conductor surrounding said tubeand a tubular inner conductor coaxial with said outer conductor andconnected to one end thereof, the other end of said outer conductorbeing closed, said tube being received coaxially within said innerconductor to an extent at which a portion of said anode is surrounded bysaid inner conductor to effect capacitive coupling therebetween, saidenvelope acting as dielectric between said anode and said innerconductor, said grid being connected to said closed end of said outerconductor.

DAVID ZAAYER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,278,210 Morton Mar. 31, 19422,284,733 Haefi June 2, 1942 2,312,723 Llewellyn Mar. 2, 1943 2,402,600Chevigny et a1 June 25, 1946 2,408,355 Turner Sept. 24, 1946 2,408,927Gurewitsch Oct. 8, 1946 2,409,640 Moles Oct, 22, 1946 2,412,998 LittonDec. 24, 1946

